A variety of systems and techniques are known for stacking packaged integrated circuits. Some techniques are devised for stacking chip-scale packaged devices (CSPs) while other systems and methods are better directed to leaded packages such as those that exhibit a set of leads extending from at least one lateral side of a typically rectangular package.
Memory devices are packaged in both chip-scale (CSP) and leaded packages. However, techniques for stacking CSP devices are typically not optimum for stacking leaded devices. Although CSP devices are gaining market share, in many areas, integrated circuits continue to be packaged in high volumes in leaded packages. For example, the well-known flash memory integrated circuit is typically packaged in a leaded package with fine-pitched leads emergent from one or both sides of the package. A common package for flash memory is the thin small outline package commonly known as the TSOP typified by leads emergent from one or more (typically a pair of opposite sides) lateral sides of the package.
The on-going demand for miniaturized and modular data storage has spawned a variety of memory module configurations, and many such designs employ leaded flash memory devices. Consumer electronics such as digital cameras and portable computers employ a variety of memory modules and cards to allow storage mobility and cross-platform flexibility. As with many developments in electronics, a variety of formats and configurations for storage have recently been developed such as the Multi Media Card (MMC) and the Memory Stick from Sony. One of the more successful recent portable memory storage configurations is the “Secure Digital” or “SD” format for memory cards first developed by Matsushita, SanDisk and Toshiba in the late 1990's. The “secure” part of the name for this card comes the encryption capability typically incorporated into the cards to reduced music piracy concerns. This capability is seldom employed, however.
The circuitry employed in a typical memory card is often a flash memory die or flash circuit in a specialized package integrated into a plastic casing configured to comply with the relevant dimensional requirements. Use of flash memory die or specialized packaging fails, however, to leverage testing and reliability and cost advantages implicit in TSOP packaged flash memory resulting from testing and volume production of memory circuitry fabricated and packaged in that format. What is needed, therefore, is a memory card configured to employ TSOP packaged memory.
Although the art has many techniques for stacking leaded devices, a new system and method for stacking leaded package TSOP devices in a memory card format is a welcome development. Accordingly, the present application discloses improved systems and methods for electrically and thermally coupling adjacent integrated circuit devices in stacked modules configured as memory cards.